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  1. Article ; Online: High-Throughput Contractile Measurements of Hydrogel-Embedded Intact Mouse Muscle Fibers Using an Optics-Based System.

    Vonk, Leander A / Esen, Osman / Yuen, Michaela / Kirby, Tyler J

    Journal of visualized experiments : JoVE

    2023  , Issue 195

    Abstract: In vitro cell culture is a powerful tool to assess cellular processes and test therapeutic strategies. For skeletal muscle, the most common approaches involve either differentiating myogenic progenitor cells into immature myotubes or the short-term ex ... ...

    Abstract In vitro cell culture is a powerful tool to assess cellular processes and test therapeutic strategies. For skeletal muscle, the most common approaches involve either differentiating myogenic progenitor cells into immature myotubes or the short-term ex vivo culture of isolated individual muscle fibers. A key benefit of ex vivo culture over in vitro is the retention of the complex cellular architecture and contractile characteristics. Here, we detail an experimental protocol for the isolation of intact flexor digitorum brevis muscle fibers from mice and their subsequent ex vivo culture. In this protocol, muscle fibers are embedded in a fibrin-based and basement membrane matrix hydrogel to immobilize the fibers and maintain their contractile function. We then describe methods to assess the muscle fiber contractile function using an optics-based, high-throughput contractility system. The embedded muscle fibers are electrically stimulated to induce contractions, after which their functional properties, such as sarcomere shortening and contractile velocity, are assessed using optics-based quantification. Coupling muscle fiber culture with this system allows for high-throughput testing of the effects of pharmacological agents on contractile function and ex vivo studies of genetic muscle disorders. Finally, this protocol can also be adapted to study dynamic cellular processes in muscle fibers using live-cell microscopy.
    MeSH term(s) Mice ; Animals ; Hydrogels/metabolism ; Muscle Fibers, Skeletal/metabolism ; Muscle Contraction/physiology ; Muscle, Skeletal/physiology ; Sarcomeres
    Chemical Substances Hydrogels
    Language English
    Publishing date 2023-05-05
    Publishing country United States
    Document type Journal Article ; Video-Audio Media ; Research Support, Non-U.S. Gov't
    ZDB-ID 2259946-0
    ISSN 1940-087X ; 1940-087X
    ISSN (online) 1940-087X
    ISSN 1940-087X
    DOI 10.3791/65103
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Nebulin: big protein with big responsibilities.

    Yuen, Michaela / Ottenheijm, Coen A C

    Journal of muscle research and cell motility

    2020  Volume 41, Issue 1, Page(s) 103–124

    Abstract: Nebulin, encoded by NEB, is a giant skeletal muscle protein of about 6669 amino acids which forms an integral part of the sarcomeric thin filament. In recent years, the nebula around this protein has been largely lifted resulting in the discovery that ... ...

    Abstract Nebulin, encoded by NEB, is a giant skeletal muscle protein of about 6669 amino acids which forms an integral part of the sarcomeric thin filament. In recent years, the nebula around this protein has been largely lifted resulting in the discovery that nebulin is critical for a number of tasks in skeletal muscle. In this review, we firstly discussed nebulin's role as a structural component of the thin filament and the Z-disk, regulating the length and the mechanical properties of the thin filament as well as providing stability to myofibrils by interacting with structural proteins within the Z-disk. Secondly, we reviewed nebulin's involvement in the regulation of muscle contraction, cross-bridge cycling kinetics, Ca
    MeSH term(s) Humans ; Muscle Proteins/pharmacology ; Muscle Proteins/therapeutic use ; Muscle, Skeletal/drug effects
    Chemical Substances Muscle Proteins ; nebulin (02X6KNJ5EE)
    Language English
    Publishing date 2020-01-25
    Publishing country Netherlands
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Review
    ZDB-ID 283053-x
    ISSN 1573-2657 ; 0142-4319
    ISSN (online) 1573-2657
    ISSN 0142-4319
    DOI 10.1007/s10974-019-09565-3
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Lmod2 is necessary for effective skeletal muscle contraction.

    Larrinaga, Tania M / Farman, Gerrie P / Mayfield, Rachel M / Yuen, Michaela / Ahrens-Nicklas, Rebecca C / Cooper, Sandra T / Pappas, Christopher T / Gregorio, Carol C

    Science advances

    2024  Volume 10, Issue 11, Page(s) eadk1890

    Abstract: Muscle contraction is a regulated process driven by the sliding of actin-thin filaments over myosin-thick filaments. Lmod2 is an actin filament length regulator and essential for life since human mutations and complete loss of Lmod2 in mice lead to ... ...

    Abstract Muscle contraction is a regulated process driven by the sliding of actin-thin filaments over myosin-thick filaments. Lmod2 is an actin filament length regulator and essential for life since human mutations and complete loss of Lmod2 in mice lead to dilated cardiomyopathy and death. To study the little-known role of Lmod2 in skeletal muscle, we created a mouse model with Lmod2 expressed exclusively in the heart but absent in skeletal muscle. Loss of Lmod2 in skeletal muscle results in decreased force production in fast- and slow-twitch muscles. Soleus muscle from rescued
    MeSH term(s) Animals ; Humans ; Mice ; Cytoskeletal Proteins/genetics ; Heart ; Mice, Knockout ; Muscle Contraction/physiology ; Muscle, Skeletal/physiology ; Myosins ; Sarcomeres
    Chemical Substances Cytoskeletal Proteins ; Myosins (EC 3.6.4.1) ; leiomodin protein, mouse
    Language English
    Publishing date 2024-03-13
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2810933-8
    ISSN 2375-2548 ; 2375-2548
    ISSN (online) 2375-2548
    ISSN 2375-2548
    DOI 10.1126/sciadv.adk1890
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article: Case report: Adult-onset limb girdle muscular dystrophy in sibling pair due to novel homozygous

    Katz, Matthew / Waddell, Leigh B / Yuen, Michaela / Bryen, Samantha J / Oates, Emily / Garton, Fleur C / Robertson, Thomas / Henderson, Robert David / Cooper, Sandra T / McCombe, Pamela A

    Frontiers in neurology

    2023  Volume 14, Page(s) 1055639

    Abstract: Recessive pathogenic variants in the laminin subunit alpha 2 ( ...

    Abstract Recessive pathogenic variants in the laminin subunit alpha 2 (
    Language English
    Publishing date 2023-01-27
    Publishing country Switzerland
    Document type Case Reports
    ZDB-ID 2564214-5
    ISSN 1664-2295
    ISSN 1664-2295
    DOI 10.3389/fneur.2023.1055639
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Neonatal-lethal dilated cardiomyopathy due to a homozygous LMOD2 donor splice-site variant.

    Yuen, Michaela / Worgan, Lisa / Iwanski, Jessika / Pappas, Christopher T / Joshi, Himanshu / Churko, Jared M / Arbuckle, Susan / Kirk, Edwin P / Zhu, Ying / Roscioli, Tony / Gregorio, Carol C / Cooper, Sandra T

    European journal of human genetics : EJHG

    2022  Volume 30, Issue 4, Page(s) 450–457

    Abstract: Dilated cardiomyopathy (DCM) is characterized by cardiac enlargement and impaired ventricular contractility leading to heart failure. A single report identified variants in leiomodin-2 (LMOD2) as a cause of neonatally-lethal DCM. Here, we describe two ... ...

    Abstract Dilated cardiomyopathy (DCM) is characterized by cardiac enlargement and impaired ventricular contractility leading to heart failure. A single report identified variants in leiomodin-2 (LMOD2) as a cause of neonatally-lethal DCM. Here, we describe two siblings with DCM who died shortly after birth due to heart failure. Exome sequencing identified a homozygous LMOD2 variant in both siblings, (GRCh38)chr7:g.123656237G > A; NM_207163.2:c.273 + 1G > A, ablating the donor 5' splice-site of intron-1. Pre-mRNA splicing studies and western blot analysis on cDNA derived from proband cardiac tissue, MyoD-transduced proband skin fibroblasts and HEK293 cells transfected with LMOD2 gene constructs established variant-associated absence of canonically spliced LMOD2 mRNA and full-length LMOD2 protein. Immunostaining of proband heart tissue unveiled abnormally short actin-thin filaments. Our data are consistent with LMOD2 c.273 + 1G > A abolishing/reducing LMOD2 transcript expression by: (1) variant-associated perturbation in initiation of transcription due to ablation of the intron-1 donor; and/or (2) degradation of aberrant LMOD2 transcripts (resulting from use of alternative transcription start-sites or cryptic splice-sites) by nonsense-mediated decay. LMOD2 expression is critical for life and the absence of LMOD2 is associated with thin filament shortening and severe cardiac contractile dysfunction. This study describes the first splice-site variant in LMOD2 and confirms the role of LMOD2 variants in DCM.
    MeSH term(s) Actin Cytoskeleton/genetics ; Actin Cytoskeleton/metabolism ; Cardiomyopathy, Dilated/genetics ; HEK293 Cells ; Heart Failure/genetics ; Heart Failure/metabolism ; Homozygote ; Humans ; Infant, Newborn
    Language English
    Publishing date 2022-01-26
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 1141470-4
    ISSN 1476-5438 ; 1018-4813
    ISSN (online) 1476-5438
    ISSN 1018-4813
    DOI 10.1038/s41431-022-01043-8
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Prevalence, parameters, and pathogenic mechanisms for splice-altering acceptor variants that disrupt the AG exclusion zone.

    Bryen, Samantha J / Yuen, Michaela / Joshi, Himanshu / Dawes, Ruebena / Zhang, Katharine / Lu, Jessica K / Jones, Kristi J / Liang, Christina / Wong, Wui-Kwan / Peduto, Anthony J / Waddell, Leigh B / Evesson, Frances J / Cooper, Sandra T

    HGG advances

    2022  Volume 3, Issue 4, Page(s) 100125

    Abstract: Predicting the pathogenicity of acceptor splice-site variants outside the essential AG is challenging, due to high sequence diversity of the extended splice-site region. Critical analysis of 24,445 intronic extended acceptor splice-site variants reported ...

    Abstract Predicting the pathogenicity of acceptor splice-site variants outside the essential AG is challenging, due to high sequence diversity of the extended splice-site region. Critical analysis of 24,445 intronic extended acceptor splice-site variants reported in ClinVar and the Leiden Open Variation Database (LOVD) demonstrates 41.9% of pathogenic variants create an AG dinucleotide between the predicted branchpoint and acceptor (AG-creating variants in the AG exclusion zone), 28.4% result in loss of a pyrimidine at the -3 position, and 15.1% result in loss of one or more pyrimidines in the polypyrimidine tract. Pathogenicity of AG-creating variants was highly influenced by their position. We define a
    Language English
    Publishing date 2022-06-25
    Publishing country United States
    Document type Journal Article
    ISSN 2666-2477
    ISSN (online) 2666-2477
    DOI 10.1016/j.xhgg.2022.100125
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article: The Effects of Disease Models of Nuclear Actin Polymerization on the Nucleus.

    Serebryannyy, Leonid A / Yuen, Michaela / Parilla, Megan / Cooper, Sandra T / de Lanerolle, Primal

    Frontiers in physiology

    2016  Volume 7, Page(s) 454

    Abstract: Actin plays a crucial role in regulating multiple processes within the nucleus, including transcription and chromatin organization. However, the polymerization state of nuclear actin remains controversial, and there is no evidence for persistent actin ... ...

    Abstract Actin plays a crucial role in regulating multiple processes within the nucleus, including transcription and chromatin organization. However, the polymerization state of nuclear actin remains controversial, and there is no evidence for persistent actin filaments in a normal interphase nucleus. Further, several disease pathologies are characterized by polymerization of nuclear actin into stable filaments or rods. These include filaments that stain with phalloidin, resulting from point mutations in skeletal α-actin, detected in the human skeletal disease intranuclear rod myopathy, and cofilin/actin rods that form in response to cellular stressors like heatshock. To further elucidate the effects of these pathological actin structures, we examined the nucleus in both cell culture models as well as isolated human tissues. We find these actin structures alter the distribution of both RNA polymerase II and chromatin. Our data suggest that nuclear actin filaments result in disruption of nuclear organization, which may contribute to the disease pathology.
    Language English
    Publishing date 2016-10-07
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2564217-0
    ISSN 1664-042X
    ISSN 1664-042X
    DOI 10.3389/fphys.2016.00454
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  8. Article ; Online: KBTBD13 is an actin-binding protein that modulates muscle kinetics.

    de Winter, Josine M / Molenaar, Joery P / Yuen, Michaela / van der Pijl, Robbert / Shen, Shengyi / Conijn, Stefan / van de Locht, Martijn / Willigenburg, Menne / Bogaards, Sylvia Jp / van Kleef, Esmee Sb / Lassche, Saskia / Persson, Malin / Rassier, Dilson E / Sztal, Tamar E / Ruparelia, Avnika A / Oorschot, Viola / Ramm, Georg / Hall, Thomas E / Xiong, Zherui /
    Johnson, Christopher N / Li, Frank / Kiss, Balazs / Lozano-Vidal, Noelia / Boon, Reinier A / Marabita, Manuela / Nogara, Leonardo / Blaauw, Bert / Rodenburg, Richard J / Küsters, Benno / Doorduin, Jonne / Beggs, Alan H / Granzier, Henk / Campbell, Ken / Ma, Weikang / Irving, Thomas / Malfatti, Edoardo / Romero, Norma B / Bryson-Richardson, Robert J / van Engelen, Baziel Gm / Voermans, Nicol C / Ottenheijm, Coen Ac

    The Journal of clinical investigation

    2024  Volume 134, Issue 3

    MeSH term(s) Microfilament Proteins/metabolism ; Muscle Proteins/metabolism ; Muscles ; Actins/metabolism ; Kinetics ; Protein Binding
    Chemical Substances Microfilament Proteins ; Muscle Proteins ; Actins
    Language English
    Publishing date 2024-02-01
    Publishing country United States
    Document type Journal Article ; Published Erratum
    ZDB-ID 3067-3
    ISSN 1558-8238 ; 0021-9738
    ISSN (online) 1558-8238
    ISSN 0021-9738
    DOI 10.1172/JCI179111
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  9. Article ; Online: Dysfunctional sarcomere contractility contributes to muscle weakness in ACTA1-related nemaline myopathy (NEM3).

    Joureau, Barbara / de Winter, Josine Marieke / Conijn, Stefan / Bogaards, Sylvia J P / Kovacevic, Igor / Kalganov, Albert / Persson, Malin / Lindqvist, Johan / Stienen, Ger J M / Irving, Thomas C / Ma, Weikang / Yuen, Michaela / Clarke, Nigel F / Rassier, Dilson E / Malfatti, Edoardo / Romero, Norma B / Beggs, Alan H / Ottenheijm, Coen A C

    Annals of neurology

    2018  Volume 83, Issue 2, Page(s) 269–282

    Abstract: Objective: Nemaline myopathy (NM) is one of the most common congenital nondystrophic myopathies and is characterized by muscle weakness, often from birth. Mutations in ACTA1 are a frequent cause of NM (ie, NEM3). ACTA1 encodes alpha-actin 1, the main ... ...

    Abstract Objective: Nemaline myopathy (NM) is one of the most common congenital nondystrophic myopathies and is characterized by muscle weakness, often from birth. Mutations in ACTA1 are a frequent cause of NM (ie, NEM3). ACTA1 encodes alpha-actin 1, the main constituent of the sarcomeric thin filament. The mechanisms by which mutations in ACTA1 contribute to muscle weakness in NEM3 are incompletely understood. We hypothesized that sarcomeric dysfunction contributes to muscle weakness in NEM3 patients.
    Methods: To test this hypothesis, we performed contractility measurements in individual muscle fibers and myofibrils obtained from muscle biopsies of 14 NEM3 patients with different ACTA1 mutations. To identify the structural basis for impaired contractility, low angle X-ray diffraction and stimulated emission-depletion microscopy were applied.
    Results: Our findings reveal that muscle fibers of NEM3 patients display a reduced maximal force-generating capacity, which is caused by dysfunctional sarcomere contractility in the majority of patients, as revealed by contractility measurements in myofibrils. Low angle X-ray diffraction and stimulated emission-depletion microscopy indicate that dysfunctional sarcomere contractility in NEM3 patients involves a lower number of myosin heads binding to actin during muscle activation. This lower number is not the result of reduced thin filament length. Interestingly, the calcium sensitivity of force is unaffected in some patients, but decreased in others.
    Interpretation: Dysfunctional sarcomere contractility is an important contributor to muscle weakness in the majority of NEM3 patients. This information is crucial for patient stratification in future clinical trials. Ann Neurol 2018;83:269-282.
    MeSH term(s) Actins/genetics ; Adult ; Female ; Humans ; Male ; Middle Aged ; Muscle Contraction/physiology ; Muscle Weakness/genetics ; Muscle Weakness/physiopathology ; Muscle, Skeletal/pathology ; Myopathies, Structural, Congenital/genetics ; Myopathies, Structural, Congenital/physiopathology ; Sarcomeres/pathology ; Sarcomeres/physiology ; Young Adult
    Chemical Substances ACTA1 protein, human ; Actins
    Language English
    Publishing date 2018-02-06
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 80362-5
    ISSN 1531-8249 ; 0364-5134
    ISSN (online) 1531-8249
    ISSN 0364-5134
    DOI 10.1002/ana.25144
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  10. Article ; Online: Variants in SLC18A3, vesicular acetylcholine transporter, cause congenital myasthenic syndrome.

    O'Grady, Gina L / Verschuuren, Corien / Yuen, Michaela / Webster, Richard / Menezes, Manoj / Fock, Johanna M / Pride, Natalie / Best, Heather A / Benavides Damm, Tatiana / Turner, Christian / Lek, Monkol / Engel, Andrew G / North, Kathryn N / Clarke, Nigel F / MacArthur, Daniel G / Kamsteeg, Erik-Jan / Cooper, Sandra T

    Neurology

    2016  Volume 87, Issue 14, Page(s) 1442–1448

    Abstract: Objective: To describe the clinical and genetic characteristics of presynaptic congenital myasthenic syndrome secondary to biallelic variants in SLC18A3.: Methods: Individuals from 2 families were identified with biallelic variants in SLC18A3, the ... ...

    Abstract Objective: To describe the clinical and genetic characteristics of presynaptic congenital myasthenic syndrome secondary to biallelic variants in SLC18A3.
    Methods: Individuals from 2 families were identified with biallelic variants in SLC18A3, the gene encoding the vesicular acetylcholine transporter (VAChT), through whole-exome sequencing.
    Results: The patients demonstrated features seen in presynaptic congenital myasthenic syndrome, including ptosis, ophthalmoplegia, fatigable weakness, apneic crises, and deterioration of symptoms in cold water for patient 1. Both patients demonstrated moderate clinical improvement on pyridostigmine. Patient 1 had a broader phenotype, including learning difficulties and left ventricular dysfunction. Electrophysiologic studies were typical for a presynaptic defect. Both patients showed profound electrodecrement on low-frequency repetitive stimulation followed by a prolonged period of postactivation exhaustion. In patient 1, this was unmasked only after isometric contraction, a recognized feature of presynaptic disease, emphasizing the importance of activation procedures.
    Conclusions: VAChT is responsible for uptake of acetylcholine into presynaptic vesicles. The clinical and electrographic characteristics of the patients described are consistent with previously reported mouse models of VAChT deficiency. These findings make it very likely that defects in VAChT due to variants in SLC18A3 are a cause of congenital myasthenic syndrome in humans.
    MeSH term(s) Adolescent ; Child ; Diagnosis, Differential ; Female ; Genetic Variation ; Humans ; Male ; Myasthenic Syndromes, Congenital/diagnosis ; Myasthenic Syndromes, Congenital/drug therapy ; Myasthenic Syndromes, Congenital/genetics ; Myasthenic Syndromes, Congenital/physiopathology ; Vesicular Acetylcholine Transport Proteins/genetics
    Chemical Substances SLC18A3 protein, human ; Vesicular Acetylcholine Transport Proteins
    Language English
    Publishing date 2016-09-02
    Publishing country United States
    Document type Case Reports ; Journal Article
    ZDB-ID 207147-2
    ISSN 1526-632X ; 0028-3878
    ISSN (online) 1526-632X
    ISSN 0028-3878
    DOI 10.1212/WNL.0000000000003179
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